Latches with extensible buckles are well known, in particular for their esthetic appearance. They have the drawback, however, of not being able to be adjusted easily to adapt the length of the bracelet to the wearer's wrist.
Many solutions have been proposed to allow the user to adjust the latch himself, in particular without using tools.
For example, U.S. Pat. No. 2,097,055 describes a latch comprising three articulated segments, connected to a central blade. One of the segments can slide into the central blade to be placed in a series of slots determining the length of the bracelet.
Another example is described in patent application EP 1 378 185A1. The end of one of the strands of the bracelet is attached to an organ capable of sliding in a slot formed in the latch so as to make it possible to adjust the length of the bracelet. The sliding of this organ is allowed by two push-pieces equipped with hooks that engage in the mobile organ.
Each of these latches has a locking organ for locking the latch and a separate organ for adjusting the length of the bracelet.
Document US 2065581 proposes an interesting system, in which the articulated segments forming the latch are able to be placed in a housing formed by the cap of the latch. In one of the embodiments described, a second sliding element can also slide in the housing, on the side opposite the first element.
The first sliding element consists of three extensible blades, which can be placed in the housing when they are folded. To index the position of the sliding element, slots are formed in the sliding element and can cooperate with slots formed in the cap or in the second sliding element. To lock the position of the sliding element(s), a lever is pivotably mounted in the cap, and makes it possible to actuate a cam acting on an elastic blade. The pressure exerted by the latter part when it is deformed under the action of the cam makes it possible to engage the slots in one another to secure the position of the sliding elements.
The lever therefore only serves as a locking organ for the bracelet and, when the latch is unlocked, the bracelet will tend to open completely under the weight of the watch. Thus, in the event of untimely unlocking, there is a risk of the latch opening and the watch falling. Furthermore, it may also be noted that the ergonomics of such a system are not optimal, since to close the latch, it is necessary to keep the sliding elements in the desired position and simultaneously actuate the lever, these operations naturally having to be done with one hand. Lastly, when it is in the open position, the sliding elements are no longer indexed, the slots not being engaged in one another and no longer being across from one another. Also, in light of the large number of proposed notches, the previous adjustment position is not automatically found when the latch is closed again.
One of the aims of the present invention is to provide an improved version of a bracelet latch making it easier to adjust the length of the bracelet. One of the aims sought by the device according to the invention is in particular to allow a subtle adjustment of the length of the bracelet, so as to impart comfort to the user when, depending on the time of day, the temperature, or the user's activity, the user's wrist swells or contracts, causing compression or play in his watch bracelet.
One additional aim of the invention is to allow the wearer of the watch to adjust the length of the bracelet easily while the latch remains closed.